Method for distilling solid hydrocarbonaceous material



F. W. LEFFER May 19, 1953- 2,639,263 l METHOD FOR DISTILLING SOLIDHYDROCARBONACEOUS MATERIAL Filed 00T.. 5. 1948 @A a www w 5 ,j C? 4 Il f2 6 6 f A .-.-v w Huwuwwwmmmm. ly f 4 .mw

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withdrawing distilled solid particles f from the lower portion thereofinto a vertically upwardly flowing stream of hot combustion gases,obtained as set forth below, passing the resultant mixture in a connedvertical straight line path upwardly through said distillation zone tothe top portion of a downwardly moving bed of solid particles within aburning zone superimposed above the distillation zone, introducing afree oxygen-containing gas stream'to the lower portion of the burningzone and thereby burning substantially the residual carbonacecus contentfrom the solid particles and heating the residue, removing combustiongases formed in the burning step from the upper portion of the burningzone while transferring heated residual solid particles from the lowerportion thereof into direct contact with water in a confined coolingzone whereby the residual particles in the latter zone are cooled andhigh temperature steam is generated, and subsequently introducing astream or the steam thus generated to the lower portion of thedistillation zone as the aforesaid high temperature steam.

`-It is also a particular feature of the present process to supply freeoxygen-containing gas to the stream of solid particles being passed upWardly in the straight line path and `thus employ` two distinct stagesof burning carbonacecus material from the distillation residue,incomplete combustion of the carbonacecus content of the solid materialbeing effected in the confined straight line path or riser conduitduring the.

upward concurrent flow of gas and distilled solid particles from thelower portion 'of the distilling zone to the upper portion of theelevated burning zone while the combustion of the carbonaceous residuefrom the solid particles is completed in the elevated burning zoneduring countercurrent contact of the downwardly moving solid particlestherein with a second oxidizing gas stream. The path of the risingmaterial in the riser conduit or first combustion zone,pro

Vides a means for transferring heat indirectly to the distillation zone.The riser conduit defining a conned straight line path of shortestdistance between the bottom portion of the distillation zone and theupper portion of the elevated enlarged burningzone provides structurallya passageway adapted to reduce erosion and iiow resistance to a minimum.After the combustion in the enlarged burning zone, the hot substantiallyincombustible material is readily utilizable as a means for generatingsteam and in a preferred mode of operation is therefore passed to aconfined cooling or steam generating zone wherein it is contacted withwater so that it is cooled prior to its discharge from the unit andthereby generates steam which is utilized in the distillation.

A more specific embodiment of the present invention comprisescontinuously passing solid hydrocarbonaceous material in a finelydivided form to an elevated portion of a confined distillation zone andintroducing high temperature super-heated steam to the lower portion ofthis zone in an amount and at a velocity sufficient to fluidize thesolid material therein, discharging mixed vaporous distillation productsand steam from the 'upper portion of the distillation zone, withdrawingdistilled solid particles from the lower end of the distillation zone ina rst annular column and commingling the thus withdrawn particles with avertically upwardly flowing gasstream,.comprising hot combustion gases.obtained as'- hereinafter set forth, passing the resultantmixtureupwarclly through a coniined vertical-'straight line pathextending through said distillation'zone and to the upper portion of aburning zone maintained vertically above the distillationv zone anddischarging the solid particles of the mixture from the vertical pathonto the top portion of a descending bed of solid particles in theburning zone, passing a free oxygen-containing gas stream upwardlythrough the solid particles' in the burning zone and effecting thesubstantially complete burning of the carbon aceous content from thesolid particles while maintaining the descending bed in a fluidizedstate, continuously discharging hot combustiony gases formed in theburning step from the upper portion of the burning zone and the hotresidual solid particles from the lower portion thereof in a secondannular column, supplying a stream of the aforesaid hot combustion gasesto the dis,-

tilled solid particles issuingV fromwthe first an` nular column, passinga stream of the hot resi-- dual particles issuing from the secondannular column into direct contact with water in a con? fined coolingand steam generating zone to quench the hot solid particles vandsimultaneously produce high temperature steam, and passing a stream ofthe thus4 produced steam'tol the distillation zone as the aforesaid:high tempera' ture s team.

In still another specic embodiment of the invention, hot combustiongases from the burningzone are passe'din indirect heat exchangerelationship with steam produced in the aforementioned cooling or steamgeneratingzone in a manner to highly superheat the steam prior to itsintroduction to the distillation zone.` It is also contemplated that aportion of the hot combustion gases from the burning zone may be mixedin controlled proportions with air or free oxygen-containing gas streamand the resultant gas mixture utilized to transport the distilled solidmaterial from the lower portion of the dis tillation zone to the upperportion of the elevated burning zone, whereby this transport is effectedby a transporting gas stream which has an elevated temperature and acontrolled free oxygenv content less than that of airn and adapted toregulate the amount of burning in the riser conduit, while thetransporting gas stream is atthe same time made available in the properamount required for continuously transferring the distilled solidparticles. y Y

A particular advantage resides in the improved operation utilizing thetwo stageburning of the carbonacecus material remaining on thedistillation residue and the ow ofthe hot material in a verticalconiined path upwardly through the distillation zone in a mannerproviding heat transfer indirectly to the distillation zone. Anotheradvantageous feature` ofthe present operation is the use of a portionofthe hotburned ash from the burning zone to mix with "the bonaceousmaterial and to thereby dilute and preheat the latter at the upperportion of the distillation zone and aid in-maintaining it in nelydivided and freely owing state. Still another. feature of a preferredembodiment of the invention is the maintenance of a continuouslyreplenished body of water in the lower portion of the residue cooling orsteam generating zone in order that the -incornbustible solid residue ofthe shale, or other carbonaceous material, may be cooled by directquenching and then discharged as a slurry while simultaneously a portionof the water is vaporized and passed upwardly through the steamgenerating zone countercurrently to the hot subdivided solid ash orresidue descending therethrough.

In a preferred embodiment of this distillation method, superheated steamis used as the gasiform heating medium in the distillation zone,fractionation of the vaporous and gaseous products removed from thedistillation zone being.

greatly facilitated thereby. Without, however, departing from theprincipal objects and features of this distillation method it is alsocontemplated as one mode of operation thereof to employ a gasiforrnheating medium other than steam, provided such medium is substantiallyde'- void of free oxygen at the time of itsintroduction to the distllingzone. Thus, a hydrocarbon gas from an extraneous source or preferably alight gas fraction, which has been separated from the fluid distillationproducts removed from the distillation zone and usually contains lighthydrocarbons such as methane, may be..

heated to asuitably elevated temperature, gen erally substantially abovethe average temperature prevailing in the distillation zone, andthensupplied to the lower portion of the latter as the gasiform heatingmedium. The hydrocarbon gas, when used in this manner, may be heatedvthe manner herein provided, hot combustion -f gases substantially devoidof free oxygen are readily obtained by effecting the burning in thedownwardly moving relatively compact bed of solid particles in theelevated burning zone and medium to the lower. portion of thedistillation zone and into direct contact with the finely di*` 0 videdcharge undergoing distillation therein.

This mode of operation permits dispensing with theindirect heat exchangebetween hot combusgasiform heatingv media and tion gases and other whenthis mode of operation. is used', at least -enters the distillationzone.

portion -`of the heat contained-fin 'the highly heated residual solidparticles issuing from the burning zone may be recovered in the formofhigh temperature steam obtainable in the aforementioned steamgenerating zone and utilizable for effecting the fractionation of themixed fluid :distillation products and combustion gases dis-- chargedfrom the distillation zone; Thereby,

the heat requirements of both the distillationand the fractionation ofthe distillation products can be satisfied entirely by the heatgeneration in the burning operation of the present method.V

In some instances it may be desirable to mix a stream of hightemperature steam with a stream of the hot, substantially oxygen-freecombustion gases and introduce the mixed streams as the gasiform heatingmedium to the .distillation zone.

In all of the herein described modes of operation a stream of the highlyheated residual solid particles withdrawn from the burning zone may besupplied to the distillation zone in proximity to the point ofintroduction of the finely divided solid hydrocarbonaceous material tothe latter zone. vSuch stream of the highly heated particles may beintroduced directly into the upper portion of the bed of solid particlesin the distillation zone or, preferably, into the stream of the solidfresh charge immediately before the latter One advantage of utilizinghot residual particles substantially at the temperature of theirdischarge from the.

burning Zone in this manner resides in the rapid heating of the solidcharge particles through a temperature range within which theyordinarily zone, the heat supplied thereto by the hot.

,residual particles constituting, in general, a

-minor but` readily variable and controllable portion of the total heatrequirement of the distillation, a major portion of which is preferablysupplied by the gasiform heating medium in all of the aforesaid modesofoperation. It is understood, of course, that another minor portion ofsaid heat requirement may be furnished to the bed of solid particles inthe distillation zone by indirect heat transfer thereto from thevertical :straight line path or riser conduit, more particularly wheneffecting a partial combustion of the carbonaceous components from thedistilled solid particlesI in the riser conduit.

An important advantage of the present. dis-l tillation method resides inthe elevational coordination of the principal processing zones. whichpermits .the handling of the hottest solid particles without anyconveying means in the form of mechanically moving parts or gas lifts yand thereby assures greatest possible life of the apparatus parts comingin contact with these particles and greatest possible heat conservation.Thus, and because. of the finely divided state in which thev hotresidual particles are obtained under the processing conditions of thepresent method, these highly heated particles can be directedby theirown gravitational iow in a genorally downward direction fromfthe lowerpori tion of the elevated burning. zone into the coolf ing zione or"steam generator, or in .controlled streams both into the cooling zoneAand the upper 'portion of the distillation zone, through conduits ofminimum dimensions. When passing hot residual particles from the burningzone both to the cooling zone and the distillation zone, the portionsupplied to the latter is preferably smaller than that directed to theformer in the present distillation method. The elevational coordinationherein described also has the advantage of permitting the greaterportion of the apparatus requirements to be grouped in a compactprocessing area on ground level with a minimum of structural frameworkfor the support of elevated equipment.

Additional advantages and features of the present improved distillationoperation will become more apparent upon reference to the accompanyingdrawing diagrammatically illustrating one form of apparatus suitable forpracticing the invention and the following description thereof. Whilethe treatment of oil shale is generally referred to in the followingdescription it isto be understood that other hydrocarbonaceous materialssuch as coals, torbanite and tar sand, and in general hydrocarbonaceoussolids of the kind yielding a carbonized residue upon dry distillationand an incombustible residue upon combustion may be treated in thepresent process in a manner analogous to that herein described for oilshale. y

Referring now to the drawing, there are indicated hoppers I suitable tostore raw or dried comminutated shale or other solid hydrocarbonaceousmaterial. Each of the hoppers I has an outlet conduit 2 with a, feederor control valve 3,' suitable to regulate the 'ow of the solid materialand assure its continuous feeding into the line 4. Conduit 4 connectswith the side of a distillation chamber 5 at an elevated portionthereof, to which the finely divided material is charged and wherein ittravels downwardly in a relatively compact or fiuidized bed while beingcontacted with high temperature steam introduced to the lower endthereof by way of line An aeration line 1 with a control valve 8,connects with the feed conduit 4 and is available to supply steam to thefinely divided material prior to its entrance into the distillationchamber 5. The steam supplied through line l may preheat the solidmaterial, but is desirable primarily for maintaining the material inlines 4 and 2 in a movable state and insuring that it readily iiow intothe distillation zone. Instead of steam, another substantially inertgas, such as :for example a stream of the combustion or nue gas issuingfrom the heat exchanger 40, described below, may be supplied to line 1for the same purpose.

High' temperature steam or other gasiform heating medium is charged tothe lower end of the distillation chamber 5, through line 6, at atemperature of the order of from 450 C. to 750? C. and in the case ofmost shales preferably at about 50G-650 C. and is passedcountercurrently to the descending solid material in this chamber in anamount suflicient to maintain the bed of solid material in a freelyowing state and preclude agg-lorgneration of solid particles.

Fluid distillation products, substantially in a vaporous state,accumulate in admixture with the used gasiform heating medium in theupper portion of the distillation( chamber and this mixtureV is passedthrough particlel separator 9 to be discharged through the outletconduitv I0 and a'pressure regulating valve therein to a suitablefractionating and recovery systeml notI shown in the drawing'. Retainedsolid particles are returned from the lower end of the separator 9,through dipleg I I to the bed of solid material in the lower portion ofthe chamber '5.

The distilled shale particles are withdrawn from the lower portion ofthe chamber 5 through the lower leg I2 in an annular column around acentrally positioned conduit I3, at thelower end of which the particlesare caused to change their direction of flow to then pass upwardlythrough the riser conduit I3 to an upper contacting or burningI zonewithin chamber I4, Which is hereinafter referred as burning chamber andwhich is superimposed above the lower chamber or distilling retort 5. Atthe bottom end of the withdrawal leg I2, a line l5 projects into theinterior thereof and terminates at the lower end of the internal riserconduit I2. Line I5 is provided for introducing a gas stream into thelower end of the riser conduit to entrain or commingle with the finelydivided distillation residue and to transport it to the upper portion ofchamber M. Hot combustion gases, obtained as subsequently described, orwhen desired a free oxygencontaining gas stream, such as a mixture ofair and hot combustion gases, is passed through line i5 into the riserconduit I3. A valve I6 in the line I5 provides means for controlling theamount of free oxygen-containing gas entering the riser conduit from anexternal source. A valve 65 in line 56 serves to control the supply ofrecirculated hot combustion gases through line I5 to the riser conduit,as more fully described below. Y

The regulation of the total amount of gas passing through line I5 intothe riser conduit affords, in conjunction with the valves 3, a means forcontrolling the quantity of solid particles `present in the distillingretort.

In the usual oil shale distillation operation there is a certain amountof carbonaceous material still persent in the distilled particles, suchthat by the addition of air or oxygen to the hot distillation residue anoxidizing and burning operation takes place. In the operation of thepresent process either no burning or only a partial oxidation andremoval of this carbonaceous content is effected in the vertical riserconduit and accordingly, when partial oxidation is to be effected, thefreeoxygen content of the gas supplied through line I5 is controlled andgenerally is maintained at less than that of air. The complete removalof the carbonaceous content is effected in the burning chamber I4, wherethe nal temperature of the particles can be controlled readily andclosely. A free oxygen-containing gas stream, preferably air, issupplied to the lower end of the burning chamber I4 through line Il,having a control valve I 8, and passes upward- Y During the partialburningstep in the riser conduit I3, the solid particles are carried insuspension in the ascending gas stream of controlled, relatively lowconcentration of free oxy- .Whenever the carbohacbus 'matter on thesolid 1l een. tri. .en lt,..th sono parliuoie's aerei corvo arci-y beaof substantially 'greater cnpactss, density, or solids Concencontrastingconditions and oy'gen coh- 'oenti'atons in the t'vo .steps applied inone of the embodiments or the-present invention -fgatio of 'the tree.oxygen content in yeach of the .gasst'ams 'Supplied to the two hui-ningsteps "with 'formation of v.combi's'tic''ngases o? minimum vc'fitentf'eces's oiiy'gl and haimurn'content or heeft m conjuro.ionivit'h'substantaiiy oomn vplete combustion o' the carbonaceouscontent of `the distillation residue; fmOrem/er, the-combusjtion gaselldisengag frornfthe suspen'sion upon Aits discharge from the riserconduit 'i3 into the flipper portion of the 'chamberi on the one handone 'non the tooo'f ine been; this chamber on the other at substantiallyequal temperatures .one o balan'oetumiog .operation of high efficiencyis securedyiith avfminimu'm .of apparav: requirements.

'particles 'issuing fronthe lower end ofthe vdis- Stilling .retort 5 isAnsufI'c'ient yfor furnishing, b y the burng 'thereontheheatrequirements of theprocess, additional heat maybe generated by thebluni'ng fof fuel from -an external source .of l

:supply in the burning `'ope`ration already def'scrib'e'd. For thispurpose, burner port I9 is ,provided at a sit'able poiht of the lowerperiphery of the burning'. chamber 14, and `if so dosired ltito or "more'of suchjourner p r`J`1 ts -ir1ay be spaced at ,suitable .points of thewall of chamber :IML The burherport s rendered .pressure-tight,Lrelatively'to the v"atrio'splfrere surrounding the chamber I4, ,and uelor loothr fuel and airare supplied .to thetuioerjport la through.vaivectroll'ed lines 2`D 2] respectively, according t requirements.supplying only7 fuel through theblzrn'er.Y rt I9', oxygen for its comI`9 `so 'as to 'rndr'th operation self-supporting.

The tornei-:port it, moreover., fof oaruoular ouvaotogo'in ,storting'ure operation or .the ign-o oT ess'. [For thisuroosefsubotannanyLinoomusubio solid particles 'are circulated through the systemcomprising chamber .5. lse'r conduit I 3 and chamber 'f4 with the ald oline "2i and valve and with ircnatibn- .of 'gas "through xthereoirculating ripeta "and valv 553 inbre'riihy described below). Wil-eleth'rli "IS 2U 'd' is effected, at leas-t in aforesaid oitmooosfoei torhodburoor port meteor lli) the circulating materials obtain' aAsufficient temperature to permit feeding of comminuted oil shale or thelike charge through line 4 to the retort 5 at a .gradually increasingrate, with commensuratel'y increasing removal of solid particlesthro-ugh line 2li, kdepending on the nature .ofthe charge and the-distilled particles, Whereafter the system is kept on stream Vfor anextended ,period .of time, which .may amount to many months and isdetermined primarily by factors of safety in sp'ectionand repairsnecessitated -by ordinary 'wear of the equipment. Combustion in thestart- ',ing-upoperat'ion may be initiated in the .burner port fill bysuitable ignitingmeans, not show-n in thedrawingyorby chemical ignition.v

v Referring again to the normal operation of the process,A the ashorresidual, incombustible solid material obtained upon the completeoxidation .an-dneating .to the required temperature is withdrawn as adownwardly -rnoving annular column .from the lower end of chamber Illthrough the leg 2.2 which surrounds the internal riser condui-t 'i3 andwhich has outlet conduits l23 andf24 connecting therewith. l A majorportion of' the hot shale ash obtained in chamberll is transferred to acooling vcharnber 2755 through line 23 VIhaving control valve 12-5, andin this latter chamber the shale; ashis contacted and quenched with aninert fluid, `suchjas a light hydrocarbon gas or Water supplied at thelower end thereof. Where a gasiiorm heating medium, other than steam isto be utilized for supplying heat for the shale distillation, the Ine-.-dium is introduced to the heating chamber 2,5 through Aline $3, havingValve 64. For example, a .hydrocarbon gas as here'inbefore referredto,or alight gas fraction separated from the fluid distillation productsof the present process may thus be supplied through line $3. `-In theembodiment illustrated, Where water Ais `used as the quenching mediumand a source of high temperature steam, Water is supplied through line2l to the lowerend of the .chamber 25. .An outlet-leg 28 and adischargernechanism or outlet valve 2Q passes the residual material,usually at -a temperature not exceeding [100 C., into -a body of yWatermain? tained Within the chamber il. The quenched and cooled shale :ashYis further cooled in this body of Water, being. discharged -from thetank by vmeans of a conveyor 3l. In a preferredmode of operation, Waterispassed tothe interior lof tank or chamber Sli through Yline 32 and.thecontrol valve and is Withdrawn from thefupper end 'thereo'll throughAline 31B .having .valvev 35, being subsequently passed throughcirculating pump BE to line 2l, Which supplies Water tothe lower end ofthe 'chamber f2.5. Thus, the now of the Water `stre'a'n'i is such thatitis gradually raised 'in temperature prior to its Yreachingchaine ber25,; thereafter, and as it passes upwardly cot'intercil'rrently totheshale ash and. residue descendingin chamber 25,4 the "Water isvapori'zed andthe temperature of the resulting steam finally approachesthat ol. the high temperature solid material entering the upperportion.of .the zone. In 'order 'to preventfthe carrying away, of shale ash withthe steam, a particle separator v3l is placed Within'the 'upper ,portionof. the .chamber 2 5. and serves to` return the solid particles throughdropleg '38 tothe downwardly moving bed of material, and a stream ofhigh temperature steam substantially free of solid particles isdischarged from the upper end of the chamber through line 39.

A heat exchanger is provided to add superheating to the steam or othergasiform heating medium prior to its being introduced through line 6 tothe distillation retort` I-Iot combustion or flue gases from the burningchamber I4 are transferred by way of conduit 4 I, having control valve42, to the heat exchanger 40. As in the chamber 5,\a particle separatingapparatus 43 is placed within the upper portion of the burning chamberI4 in order that the ue gases may be discharged -from the upper end ofthat zone substantially free of solid particles, while recovered andcollected 'particles are returned to the downwardly moving bed withinthe chamber I4 by Way of dipleg 44. The hot flue gases passing throughthe heat exchanger 40 in indirect heat exchange relationcharged with thehot combustion gases from the burning chamber I4. In this embodiment aregulating valve 45 is placed in line 6 at a point just beyond the heatexchanger 40, and in addition a line 51 with valve 58, is connected toline 6 to provide means for withdrawing excess heating medium from theunit, or for supplying superheated steam to the fractionation system forthe iiuid distillation products, as hereinbefore described, and tovarious points of the system where high temperature steam is desired asaeration or stripping medium.

As is customary with moving bed and iiuidized processing operations, itis desirable to provide stripping steam, or other inert gaseous medium,at each of the solids Withdrawal zones for each of the contactingchambers. At the bottom of thedistillation zone is a line 46, having acontrol valve 41, connected to the withdrawal leg I2 so that steam fromline 5l or other inert stripping medium may be introduced to thelwithdrawal leg to prevent the entrainment of valuable uid distillationproducts by the distilled solid particles. Likewise, steam is alsopassed to the Withdrawal leg 22 which passes heated particles from thelower end of the burning chamber I4 to the steam generating zone 25.Preferably, and as illustrated in the drawing, superheated steam issupplied to the Withdrawal leg 22 by way of line 48 having control valve49, the line 48 being connected to and supplied with steam from line 5 Yjust beyond the heat exchanger 40. Thus, high temperature superheatedsteam is utilized at this point for the dual purpose of both precludingentrainment of oxygen in the solid particles passing to the steamgenerating zone, and preventing undue cooling of these particles. Foranalogous purposes, and for the purpose of assuring ready flow of thesolid particles, superheated steam may also be introduced throughsuitable connections (not shown in the drawing) from line 51 into line24 (more fully referred to below) at a point in proximity of the valve52 on the upstream side of the latter. A line 5I] with valve 5I is alsoprovided at the conduit 23 for the supply of a hot gasiform aeratingmedium, such as steam from line 5l', in order that the solid materialmay if necessary be aerated and its gravitational flow facilitated as itpasses from the burning zone into the cooling or steam generating zone2'5.

A desirable feature of the improved shale procing the stripping zones`I2 and 22 of an annular shape and positioned uniformly around thecentral riser conduitI I3 in heat exchange relationship therewith, sincethe higher the temperature, the more efficient'is the stripping. Thoughnot indicated in the drawingit is contemplated that if desired, flowdistributing 'grids or vertically spaced horizontal perforated platesmay be positioned around the riser conduit in each of the strippingzones I2 and 22. 'A y v Referring now tothe line 24 having valve 52, itmay be desirable during'the normal operation of the process tocontinuously'pass a portion, generally a minor portion, of the heatedparticles issuing from the lower endof the burning chamber I4 into thefeed conduit '4 in order that the hot shale ash may commingle with thefresh comminuted shale charge vand preh'eat the latter immediately priorto its entrance into the distillation zone of chamber 5. This method ofoperation also permits a given quantity of hot `ashlike material to bepresent within the moving or iiuidized bed-of chamber 5, whereby adilution effect is obtained counteracting the baking tendency ofthe'fresh'shale particles particularly during an early stage oftheir'distillation'.

One of the important features in the ,operation of the present process'is the recycling of a portion o f the hot flue gas streamsubstantiallyat its temperature of discharge from the burning chamber I4 through line4| tothe line I5 which enters the withdrawal leg I2 'atthe bottom of thedistillation zone and chamber 5.v Conduit 53, with valve 54, serves toconnect the line 4I with pump or blower 55 and the line 56 which in turndischarges through control valve into line I6 whereby flue gas may beused as' the medium for transporting the particles through riser I3 tothe burning'chamber -I,4,or, alternately, for both this purpose and as adiluent to mix with air or other oxygen-containing` gas'lstrelamentering the lower end of the verticalriser conduit I3: The supply of aportion of hot spent or substantially oxygen-free combustion gases fromthe top -of burning zonenI4l'through'thelinej53, `thus provides anadvantageous means for not Vonly precluding the loss of sensiblei heat',from the "distilled solid particles duringtheir transfer, lto theburning chamber, 4but actually' increasing 'the temperature ofthis'stream of solid particlesjand it alsoprovides an advantageousmeansfor obtaining, upon admixturev with air supplied through line I5 andvalve I6, a preheated gas stream of controlled oxygen content lower thanthat of air. The connecting line 59- and valve 60 provide means forpassinghot combustion gases, substantially devoid of'free oxygen, fromthe line 56 to line 6, whereby thev combustion gases may serve asgasiform heat-supplying I nedium being charged to the distillationchamber 5. It should be understood from the foregoing, however, that inthe preferred mode `ofoperation, lthe recirculated combustion gasesjare'not passed into the distillation retort itselfor into contact withthe distillation charge and that in Iany event the recirculated hotgases provide 'a desirable transporting medium or a diluent for the airentering line I6, and a hot gas stream adequate in quantity fortransporting the distilled particles through the conduit I3 to theburning ychamber I4. A line 6I with valve 62, connects with` line 4Inear the top of the combustion lchamber I4 and provides means forventing the air 'system at the starting-up'-and 'termination o f anoperation as een for withdrawing not complici-,ion gases in such amountsas are not required within the illus= trated systei'n during itsoperation,

In` the process as describdf the iolintei'cuil low ol' gaseous hea-tingmedium anti liely divided solid in the distillation acne materiallybenefits ine'- valuable hydrocarbon cil fractions desired as priinaiyproducts oi the process and reduces to a minimun the undesirablecracking or pyrolytic decomposition reactions which would result invexcessive gas formation. Crack-ing will take place rto seine extent inthe lower hotter porn tion of the distilling chamber S while primarily anoni-destructive distillation takes place in the upper or relativelycool portion thereof;

in carrying outthe process, .the temperature distributionin thed'stilling Zone 'or retort 5 will depend' largely on the initialcomposition. oi the solid. chargeand to some extent also 'on the exstent ofturbulency which will be greater in a well nuidized bed relativeto a more coinpact bed, but in either case' such temperaturedistribution is suicient to carbonize tarry components 'of the solidparticles so as to permit the 'distillation resi-Y dueto .remain in afinely divided state for its l.

transfer into the riser conduit i3 and there through to the upperportion oi chamber I4 the combustion zone inthe latter. Most oi thecommonly available oil shares are distill'able in thepresent process attemperatures of the solid particles of. from about 425. to about 500 C.,and the maximum temperature of the solid material in the distillationchamber 5 is seldom required to exceed about 550 C. As a rule, atemperature substantially above the average temperature pre; f

vailing in the retort 5 andA less than 750 C.,- and more particularly offrom 500 to 650 C. will be ample for the steam or other gasiform heatingmedium to effect the distillation of mostkinds of oil shale anrltorbanite at a suitable ratio vof sol-id material to gasiform heatingmedium* A relatively low heating medium temperature and ayhigh ratio ofthe medium to solid vcharge are desirable for a maximum recovery ofhydrocarbon oils, whereas the higher temperatures andV rela tively lowerratios of gasiforrn heating medium to solid charge may `beernployed.when it is pre-'- ferred to -sacriceototal yield of oilxin` order toobtain primarily vlow boiling hydrocarbon oil fractions. In the latter-case the solid particles will movey essentially as acompact bed downwardly through retort -5 countercurrently to suf"- ficient gasiformheating medium to preclude kbaking or agglomerating of the vshaleparticles and the highest boiling volatilizable components of the oilshale, or other bituminous solids, will be retaineolin the distillingretort and will'eventually be cracked into `lower boiling k'componentsand carbonace'ous or non-volatilizable residue. High temperatures of thevsteam or other gasifornl heating medium and high ratios of the mediumtoi solid charge, that is to say ratios of gasiform medium to so-lidparticles ysuch that the descendnig nedy in the distan-ng retort ismaintained in a well fluidiae'd dense phase and a -dilute phaseofconsiderably lower concentration of solid particles is maintainedabove the bed, are generally preferred for optimum recovery of normallyliquid hydrocarbonaceous distillation products.

The process may be operated under any suitable pressure and normallywill be carried out atabout atmospheric or a moderateIsupere-atmospheric presslrrmup to yabout atmospheres, although it jniayin some 4cases be desi-red to operate meer his'gerrprssure iso, topermit relatively sinall diniensioning ci the apparatus for a given tin"ughput of materialani-to permit obtaining 'steam under relatively highpressure. Slight pressure differentials will ot cou-rse exist betweenthe different .zones-ori the in order that adequate oW o materials maybe made from one sone to anoniem` In the apparatus illustrated in thedrawing continuousI new of the solids and particularly gravitational newoi the hot residua-l material from the burning zone isgifeatly faciliataies by the @inerenti elevations of the elements l, 5, l l and i5;relative to other The neness to which fresh shale is pulverizea ground'will depend somewhat on economic considerations andas to 'the exactcontem-plated operation or the Particle airain-. 'eters or greater than5 millimeters are generally unclesiredin the present method., Where afluid, izeadense phase operation Vis desired the uis. till'ation zone orthe b 'ng' chamber or in both, a particle size of; approiriniateiy treinc 'l to 0.8 millimeter in diameter is preferred for the hyere-Vearbonaceous charge; .however with a moving: bed type of operation, aparticle size or from approio imately n.1 to about 3io rnillinietersfindiameter is generally utilizable, and with su'iiiolent` transporting gasthe resultant distilledparticles may in either 'case be napster-'redwithout' diiliculty from thek lower end of the distillation. retort E tothe upper portion oi the burning 'chamber t4.

When itt is desi-red to produce a maximum amount of` high temperaturesteam within kthe residue cooling or steam generating' zone 25, arelatively high temperature should. be maintained in the upper bumingzone within chamber it. Normally, the residual solid particles may beheated to a temperature oil theorder of. 600-'7'50 without sinterinesome-oil Ashales yield residues which permit heating tuv temperatures ofthe order of 800 C'.. without 'sinte'ring However, the highesttemperature in chamber I4 should always be- `kept a sufficient amount,that is vat least about 25 C1.,.below the temperature at which theash-like residue tends toz-sinter yor clinker, and such temperaturedepends on the particular hydrecarhonaceous charge treated: and.. can bedetermined i-'ea-dily :by laboratory tests on a sample Aof such:oh-argeprior' to treatment "or the latter inv the present process .nshereinbeiore noted, where the distillation resi-dueI in the chainsberlil has insuificient carbonaceous content t0 burn and raise themater-rail at least to the prefferr'ecl temperature which is of theorderof 600 to 675 C., vor., if sodesiredz, tov-a1 higher :permissibletemperature to about Aor 800 C. then ad ditional heat may begeneiiatedbytsupplying sufnoi-enteXtraneousruel-or combustible-byeprodocts of theprocess to the bur-ner port itil, so ithat lthe heat and steamlrequirernents oil the process will be met. The heateconoiny of.fthisfprocessis inaterially enhanced ythcrolli-lilly insulating @theretort 5,- the combustion chamber i4, the residue cooling chamber 25,and the variousfconnectihg conduits external -to these-chambers andcarrying high VVtemperatin-.e-strearnsvso as elio-limit loss oi heatle-y vradiation toa minimum. v'li-lieattransu ier from the-centralriser'lconfduit t3 may be in creased-by providing. it Aon :itsoufterwallalong -the portion Athereof `w-itl'iin the 'retort 15', and, moreparticularly the ,portionicominginto contact vwith the descending leedin ythis retort, withpreferably longitudinal yfins yof =metallicmaterial, 'and heat equalization between' Ithe lupper iportionioioontl-uit i3 andI the bed -surromjiding itchamber Heiney;@similari-y; iosterediibil longitudinal ruis along the. latterportion.Heat contained in the combustion gases withdrawn from the system throughlines 6I and/'or discharged at lowered temperature from heat exchanger4B may be utilized with considerable advantage in the drying of theshale charge prior to supplying the latter to the distillation retort 5.Such drying may be effected after comminution of the solid material, ifso desired, and in any event should be carried out in a manner assuringthe maintenance of the solid charge at temperatures below about 200 C.duringV the drying operation.

I claim as my invention:

l. A method for distilling solid hydrocarbonaceous material whichcomprises continuously -passing said material in finely divided formdownwardly through a conned distillation zone and therein contactingsaid material with an upwardly ilowing gasiform heating mediumsubstantially devoid of free oxygen, discharging mixed iiuiddistillation products and heating medium from the upper portion of saiddistillation zone and withdrawing a stream of distilled solid particlesfrom the lower portion thereof into a vertically upwardly iiowing gasstream comprising hot combustion gases, obtained as hereinafter setforth, passing the resultant mixture in a confined vertical straightline path upwardly to the top 4portion of a downwardly moving bed ofsolidjparticles. maintained in a confined burning zone superimposedabove said distillation zone, said conned straight line path extendingthrough and in indirect heat exchange with said material in thedistillation zone and said bed of solid particles in the burning zone,introducing a free oxygen-containing gas stream to the lower portion ofsaid burning zone and thereby burning substantially the residualcarbonaceous content from the solid particles in said downwardly movingbed, continuously removing hot combustion gases formed in the burningstep from the upper portion of said burning zone and hot' residual solidparticles from the lower portion thereof and supplying a portion of saidhot gases to said stream of distilled solid particles withdrawn from thedistillation zone, passing a stream of the hot residual solid particleswithdrawn from the burning zone in a generally downward directionsubstantially by its own gravity and at its temperature of dischargefrom said burning zone into a cooling zone and therein contacting thesame with water so that said stream of residual particles is cooled andhigh temperature steam is generated, passing steam thus obtained intoindirect heat exchange with a second portion of the hot combustion gasesremoved from the burning zone and thereby superheating the steam to atemperature substantially above that prevailing in the distillationzone, and introducing a stream of the thus superheated steam as saidgasiform heating medium to the lower portion of said distillation zone.Y 2. A method for distilling solid hydrocarbonaceous material whichcomprises continuously passing a stream of said material in finelydivided form downwardly through a conned distillation zone and thereincontacting said material with an upwardlyiiowing gasiform heating mediumsubstantially devoid of free oxygen, discharging mixed fluiddistillation products and heating medium from the upper portion of saiddistillation zone and withdrawing a stream of distilled solid particlesfrom the lower portion thereof into .a vvertically :upwardly iiowingfree 16 oxygen-containing gas stream, partially burning carbonaceouscomponents from the distilled solid particles while passing them inadmixture with said oxygen-containing gas stream in aconiined verticalstraight line path upwardly to the top portion of a downwardly movingbed of solid particles maintained in a confined burning zonesuperimposed above said distillation zone, said coniined straight linepath extending through and in indirect heat exchange with said materialin the distillation zone and said bed of solid particles in the burningzone, introducing another free oxygen-containing gas stream to the lowerportion of said burning zone and thereby burning substantially theresidual carbonaceous content from the solid particles in saiddownwardly moving bed, continuously removing hot combustion gases formedin the two burning steps from the upper portion of said burning zone andhot residual solid particles from the lower portion thereof, passing astream of the hot residual solid particles withdrawn from the burningzone in a generally downward direction and substantially by its gravityand at its temperature of discharge from said burning zone into acooling zone and therein contacting the same with water so that saidstream of residual particles is cooled and high temperature steam isgenerated, passing steam thus obtained into indirect heat exchange witha stream of hot com-v bustion gases removed from the burning zone andthereby superheating the stream to a temperature substantially abovethat prevailing in the distillation zone, and introducing a stream ofthe thus superheated steam as said gasiform heating medium to the lowerportion of said distillation zone.

3. A process which comprises contacting iinely divided solidhydrocarbonaceous material with superheated steam in a distillationzone, removing residual solid particles from said zone and suspendingthe same in a gaseous transporting medium, transporting said residualparticles in suspension in said gaseous medium to a burning zone,burning carbonaceous matter from the residual particles in thelast-named zone, removing the resultant combustion gases from theburning zone and utilizing a portion thereof as at least a part of saidtransporting medium, withdrawing hot solid particles from the burningzone and discharging the same into a body of water, thereby generatingsteam, passing the latter in indirect heat exchange with another portionof said combustion gases to superheat the steam, and introducing thesuperheated steam to said distillation zone. 4. The process of claim 3further characterized in that said gaseous transporting medium containsoxygen and in that sai-d residual particles are subjected to partialcombustion while in transit from the distillation zone to the burnmgzone,

5. A process which comprises contacting iinely divided solidhydrocarbonaceous material in a confined distillation zone at adistilling and carbonizing temperature with upwardly iiowing combustiongases produced as hereinafter set forth, discharging mixed gases andvaporous -distillation products from the upper portion of saiddistillation zone, removing carbonized solid particles continuously fromthe lower portion of said distillation zone and suspending them in agaseous transporting medium, transporting said carbonized particles insuspension in said gaseous medium to-a Separate conned burning zoneandyfrom the lower portion of said burning zone and said combustiongases from the upper portion thereof and utilizing a portion of saidcombustion gases as at least a part of said transporting medium,commingling said hydrocarbonaceous material with a stream of saidwithdrawn hot residual particles at substantially the temperature oftheir removal from the burning zone and at a rate at which only aportion of the heat requirements for the distilling and carbonizing ofsaid hydrocarbonaceous material is supplied by said stream of residualparticles to said distillation zone, and introducing another portion ofsaid combustion gases substantially at their temperature of withdrawalfrom said burning zone into the lower portion f said distillation zoneat a rate sufcient to introduce thereto the remaining portion of saidheat requirements.

6. A process which comprises continuously passing finely divided solidhydrocarbonaceous material downwardly through a confined distillationzone and therein contacting the same at a distilling and carbonizingtemperature with upwardly flowing combustion gases produced ashereinafter set forth, discharging mixed gases and vaporous distillationproducts from the upper portion of said distillation zone, withdrawingdistilled and carbonized solid particles continuously from the lowerportion of said distillation zone and passing them in a restrictedstream into an elevated portion of a separate confined burning zone,supplying an oxidizing gas to the lower portion of said burning zone andtherein burning residual carbonaceous matter from the particles so thatcombustion gases practically devoid of free oxygen and having asubstantially higher temperature than said distilling and carbonizingtemperature are formed, continuously discharging said combustion gasesfrom the upper portion of said burning zone and hot residual particlesfrom the lowerp0rtion thereof, commingling said hydrocarbonaceousmaterial with a stream of said withdrawn hot residual particles atsubstantially the temperature of their removal from the burning zone andat a rate at which only a portion of the heat requirements for thedistilling and carbonizing of said hydrocarbonaceous material issupplied by said stream of residual particles to said distillation zone,and introducing a stream of said combustion gases substantially at theirternperature of withdrawal from said burning zone into the lower portionof said distillation zone at a rate sucient to introduce thereto theremaining portion of said heat requirements.

7. A process which comprises contacting finely divided solidhydrocarbonaceous material in a confined distillation zone at adistilling and carbonizing temperature with an upwardly flowing streamof combustion gases produced as hereinafter set forth, discharging mixedgases and Vaporous distillation products from the upper portion of saiddistillation zone and withdrawing distilled and carbonized solidparticles continuously from the lower portion thereof into atransporting gas to form a suspension of carbonized particles in saidtransporting gas, passing said suspension in a restricted streamupwardly through an elongated passageway to the top pori8 tion ofadown'wardly moving bed of lsolid particles maintained in a confinedburning zone .of higher elevation than that of said distillation zone,introducing a free oxygen-containing gas stream into the lower portionof said burning zone and regulating its rate of supply to saiddownwardly moving bed so that carbonaceous material is.. burned from theparticles therein with .the formation of combustion gases practicallydevoid of free oxygen and having a substantially higher temperature thansaid distilling andv `carbonizingtemperature, continuously removing theresultant hot combustion gases from the upper portion of said burningzone and commingling a stream thereof as at least a major portion of theaforesaid transporting gas with said particles being withdrawn from thedistillation zone, flowing a restricted stream of hot residual particlesin a generally downward direction from the lower portion of said burningzone substantially by gravity and substantially at `its temperature ofdischarge from said burning zone into said nely dividedhydrocarbonaceous material, maintaining the flow of said stream ofresidual particles at a rate to furnish only a portion of the heatrequirements for the distilling and carbonizing in said distillationzone, and introducing another stream of said hot combustion gasessubstantially at their temperature of withdrawal from said burning zoneinto the lower portion of said distillation zone at a rate sufficient tointroduce thereto the remaining portion of said heat requirements.

8. A process which comprises contacting finely divided solidhydrocarbonaceous material with a superheated gasiform distilling mediumin a distillation zone, removing residual solid particles from said zoneand suspending the same in a gaseous transporting medium, transportingsaid residual particles in suspension in said gaseous transportingmedium to a burning zone, burning carbonaceous matter from the residualparticles in the last-named zone, removing the resultant combustiongases from the burning zone and utilizing a portion thereof as at leasta part of said transporting medium, withdrawing hot solid particles fromthe burning zone and discharging the same into a particle cooling zoneand into direct contact therein with a fluid distilling medium andthereby transforming the latter into a heated gasiform distillingmedium, passing the latter in indirect heat exchange with anotherportion of said combustion gases to superheat said heated distillingmedium, and introducing thus superheated gasiform distilling medium tosaid distillation zone.

9. The process of claim 8 further characterized in that fluiddistillation products are removed from said distillation zone and ahydrocarbon-containing light gas fraction is separated from saiddistillation products and introduced as said fluid distilling medium incontact with the solid particles in said particle cooling zone.

FREDERICK W. LEFFER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,524,784 Bartolomeis Feb. 3, 1925 1,983,943 Odell Dec. 11,1934 1,984,380 Odell Dec. 18, 1934 2,327,175 Conn Aug. 17, 1943(Additional references on following page) 301,975 Great Britain Dec. 13,1928

1. A METHOD FOR DISTILLING SOLID HYDROCARBONACEOUS MATERIAL WHICH COMPRISES CONTINUOUSLY PASSING SAID MATERIAL IN FINELY DIVIDED FORM DOWNWARDLY THROUGH A CONFINED DISTILLATION ZONE AND THEREIN CONTACTING SAID MATERIAL WITH AN UPWARDLY FLOWING GASIFORM HEATING MEDIUM SUBSTANTIALLY DEVOID OF FREE OXYGEN, DISCHARGING MIXED FLUID DISTILLATION PRODUCTS AND HEATING MEDIUM FROM THE UPPER PORTION OF SAID DISTILLATION ZONE AND WITHDRAWING A STREAM OF DISTILLED SOLID PARTICLES FROM THE LOWER PORTION THEREOF INTO A VERTICALLY UPWARDLY FLOWING GAS STREAM COMPRISING HOT COMBUSTION GASES, OBTAINED AS HEREINAFTER SET FORTH, PASING THE RESULTANT MIXTURE IN A CONFINED VERTICAL STRAIGHT LINE PATH UPWARDLY TO THE TOP PORTION OF A DOWNWARDLY MOVING BED OF SOLID PARTICLES MAINTAINED IN A CONFINED BURNING ZONE SUPERIMPOSED ABOVE SAID DISTILLATION ZONE, SAID CONFINED STRAIGTH LINE PATH EX TENDING THROUGH AND IN INDIRECT HEAT EXCHANGE WITH SAID MATERIAL IN THE DISTILLATION ZONE AND SAID BED OF SOLID PARTICLES IN BURNING ZONE, INTRODUCING A FREE OXYGEN-CONTAINING GAS STREAM TO THE LOWER PORTION OF SAID BURNING ZONE AND THEREBY BURNING SUBSTANTIALLY THE RESIDUAL CARBONACEOUS CONTENT FROM THE SOLID PARTICLES IN SAID DOWNWARDLY MOVING BED, CONTINUOUSLY REMOVING HOT COMBUSTION GASES FORMED IN THE BURNING STEP FROM THE UPPER PORTION OF SAID BURNING ZONE AND HOT RESIDUAL SOLID PARTICLES FROM THE LOWER PORTION THEREOF AND SUPPLYING A PORTION OF SAID HOT GASES TO SAID STREAM OF DISTILLED SOLID PARTICLES WITHDRAWN FROM THE DISTILLATION ZONE, PASSING A STREAM OF THE HOT RESIDUAL SOLID PARTICLES WITHDRAWN FROM THE BURNING ZONE IN A GENERALLY DOWNWARD DIRECTION SUBSTANTIALLY BY ITS OWN GRAVITY AND AT ITS TEMPERATURE OF DISCHARGE FROM SAID BURNING ZONE INTO A COOLING ZONE AND THEREIN CONTACTING THE SAME WITH WATER SO THAT SAID STREAM OF RESIDUAL PARTICLES IS COOLED AND HIGH TEMPERATURE STEAM IS GENERATED, PASSING STEAM THUS OBTAINED INTO INDIRECT HEAT EXCHANGE WITH A SECOND PORTION OF THE HOT COMBUSTION GASES REMOVED FROM THE BURNING ZONE AND THEREBY SUPERHEATING THE STEAM TO A TEMPERATURE SUBSTANTIALLY ABOVE THAT PREVAILING IN THE DISTILLATION ZONE, AND INTRODUCING A STREAM OF THE THUS SUPERHEATED STEAM AS SAID GASIFORM HEATING MEDIUM TO THE LOWER PORTION OF SAID DISTILLATION ZONE. 